TY  - BOOK
AU  - Grim,Ralph E.
AU  - Allen,Victor T.
TI  - Petrology of the Pennsylvania underclays of Illinois,
T2  - Illinois.  State geological survey.  Report of investigations
AV  - QE105 .A25 no. 52
PY  - 1938///
CY  - Urbana, Ill.
PB  - Printed by authority of the state of Illinois
KW  - Petrology
KW  - Illinois
KW  - Clay
N1  - cover title; At head of title: State of Illinois ... Department of registration and education ... Division of the State geological survey; Reprinted from the Bulletin, Geological Society of America, vol. 49, 1938; "Works to which reference is made": p. 1500-1510
ER  -